• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 274 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DS90UB934-Q1: DS90UB934-Q1 IDX

user5792115
Prodigy 90 points
Part Number: DS90UB934-Q1

HI

There's a problem with the I2C communication that address set by IDX is not correct.

We changed the divider resistor and set address as 0X38 but only 0X30 is detected.

Then we remove the 0.1uF condensor besides and the address is OK .

 

My question:

1.When will the 934IC detect IDX voltage during power up? I guess the reason is that IDX voltage rising speed is slow due to condensor and the 934IC detects it too early. 

0<0X30 Voltage<0.131*VDD18,

0.525*VDD18<0X38 Voltage<0.592*VDD18

 

2.Does the IC only detect IDX voltage at power up sequence or it will  keep dectecting while working?

 

3.What's the use of 0.1uF condensor? I compare to other LVDS IC and seems TI prefer to add the condesor in Des IC, bu no condensor in Ser IC. Any concern for that?

Thanks.


  • 0
    TI__Mastermind 30515 points

    Hi, pls check below comments:

    1. IDX is strapped after PDB is stable

    2. IDX just is strapped once after power-on

    3. the 0.1uf cap. is used for noise filtering. ideally if your system is clean, this cap. is not must.

    for your issue, it is simple to measure the pin status during power-on stage to better understand what happened in your system.

    regard,

    Steven

  • 0 in reply to Steven(Shenzhen) Shi
    Prodigy 90 points

    Hi

    I checked the waveform and the IDX voltage was indeed affected by the cap for abou 10ms.

    With the cap:12.2ms

    without the cap:1.7ms

    According to your comment IDX is strapped after PDB is stable, so I want to know:

    1. How to judge PDB is stable, port detecting for several times?

    2. How long is the time from PDB stable to IDX strapped? 10ms is a little long for that?

    Thanks

  • 0 in reply to user5792115
    TI__Mastermind 30515 points

    Hi, so the cap. in your system would impact the strapped value? for your issue, pls check:

    1. pls check the power-on sequence request in d/s, the PDB is active after VDD is stable, and PDB should be ~90% as well

    2. it straps the data within 10ms.

    best regards,

    Steven